1. Field of the Invention
The present invention relates to a deformation or crumple element of a rail-borne vehicle which is disposed in the region of at least one deformation zone located on the end side of the vehicle, wherein the deformation element is formed as a tubular hollow box.
2. Description of the Prior Art
For financial reasons and reasons relating to safety technology, deformation zones are usually provided in the region of the ends located on the longitudinal side of a rail-borne vehicle. On the one hand, this serves to obviate or reduce any damage to the vehicle in the event of an accident, on the other hand vehicle passenger safety is thereby increased. The parts of a rail-borne vehicle which are most frequently directly involved in accidents are the front and rear carriage end region, since most accidents are rear end collisionsxe2x80x94in the case of a train consisting of several coupled carriages individual carriages can collide together in an accidentxe2x80x94or are head-on collisions involving other traffic participants or obstacles.
Therefore, in order to protect a rail-borne vehicle tubular deformation elements which can be compressed and folded in the event of a sufficiently strong force effect are integrated in the prior art into the front and mostly also into the rear vehicle face. This feature serves to use up some of the kinetic energy, which acts upon the vehicle, for the deformation of the deformation element. Reducing the kinetic energy in this way serves also to reduce the loading which acts upon the rest of the rail-borne vehicle.
U.S. Pat. No. 4,492,291 disclose a device for protecting an unloading vessel against damage caused by falling unloading containers. For this purpose, the base of the unloading vessel is provided with a damping element which comprises two plates which lie one on top of the other and which are mutually connected via tubular deformation elements, wherein the longitudinal extension of the tubular deformation elements is substantially perpendicular to the surface of the plates. In order to improve the characteristic of the introduction of force into the deformation elements in the event of an unloading container impacting against the damping element, an end region of the deformation elements comprises an indentation in the sidewalls.
JP07145842 describes a tubular deformation element for a car, wherein an end region of the deformation element comprises a lateral indentation. The object forming the basis of JP07145842 is to absorb an impact as effectively as possible by means of a light-weight aluminium construction.
By reason of the substantial intrinsic weight and the associated high kinetic energy of a rail-borne vehicle, it is still possible for extremely high peaks of force to occur during accidents when conventional deformation elements are used, for which reason the solution disclosed in JP07145842 is not suitable for rail-borne vehicles.
Typically, the attempt is made to obviate the production of high force peaks in that mutually separately installed deformation elements, which are designed as straightforward tubular hollow bodies mostly having an approximately square cross-section, are integrated in parallel adjacent to each other into the vehicle face, wherein the longitudinal sides of the deformation elements are disposed in parallel with respect to the direction of travel. Conventionally, these deformation elements are affixed in the head regions of the vehicle underframe and are connected together by means of a transverse beam acting as a bumper. The entire vehicle""s deformation characteristic to be achieved determines how many deformation elements are used and whether these deformation elements are installed at only one or both ends of a carriage.
A disadvantage of the known devices is that undesirably high force peaks can nevertheless occur before the deformation elements fold, as the trigger force of the typically used deformation elements is ca. three times as high as the average deformation force thereof.
The term trigger force is understood to refer to the force which must be applied at the very least in order to initiate a plastic deformation of the deformation element. If the deformation procedure is described with the aid of a force-path diagram, then the amplitude of the maximum occurring force peak corresponds to the trigger force. In other words, the trigger force is the maximum force occurring during the deformation procedure. The average deformation force corresponds to the mean value of the progression of force in the aforementioned force-path diagram. However, the level of energy conversion is determined by the average deformation force. Therefore, it is desirable to achieve this range as quickly as possible during a deformation. In order to achieve the desired deformation characteristic, the trigger force would have to be at the level of the average deformation force. However, no structural deformation element is known which can solve this problem.
In order to prevent the high force peak which occurs in the event of an accident from damaging the rail-borne vehicle or injuring vehicle passengers, the remaining vehicle structure must therefore be designed to be correspondingly more robust and heavier, whereby the value of the useful load of the rail-borne vehicle is reduced and production costs are also increased.
In view of the state of the art described above, it is an object of the invention to provide a deformation element, wherein the trigger force is reduced to the level of the average deformation force of said deformation element, whereby the intrinsic weight of rail-borne vehicles and the production costs thereof can be reduced substantially.
This object is achieved in accordance with the invention by virtue of the fact that at least one sidewall of the deformation element, which is formed with a polygonal cross-section, comprises an inwardly directed indentation, wherein the indentation is provided on the longitudinal-side end region of the deformation element remote from the rail-borne vehicle underframe.
By virtue of the arrangement of at least one indentation in the deformation element, it is possible to reduce the trigger force to the level of the average deformation force.
In order to reduce the trigger force, it is advantageous that the indentation is provided in an end region of the deformation element lying in the direction of travel, since this end region is the first to absorb the dynamic loading which occurs in the event of an accident. During a deformation, the level of the average deformation force is achieved immediately in this manner without the occurrence of high force peaks.
In accordance with one cost-effective embodiment which is easy to produce, two mutually opposite-lying indentations are disposed in mutually parallel sidewalls of the deformation element.
It is possible to achieve extremely favourable deformation characteristics by virtue of the fact that the deformation element comprises a substantially square cross-section.
In order to improve the deformation characteristic, sidewalls which are in contact with the at least one sidewall, which comprises an indentation, are formed on the contact points with the indentation in such a manner as to have an identical cross-section thereto.
In accordance with one advantageous embodiment, the cross-section of the deformation element comprises a side length which amounts to between 100 and 200 mm.
In order to guarantee a sufficiently large deformation path, the length of the deformation element preferably amounts to between 800 and 1200 mm.
In one advantageous embodiment, the wall thickness of the deformation element amounts to between 3 and 7 mm.